29 



The two principal constituents of bone are cartilage and 

 phosphate of lime ; the proportions of the former being about 

 39 to 34 per cent., and that of the latter, from 50 to 60 per 

 cent, of the entire bone. The bone-earth may be dissolved 

 out by dilute hydrochloric acid (one part of strong acid to five 

 parts of water). The cartilage remains unaffected and retains 

 the form of the bone. This is really a curiosity which may 

 easily be obtained in the manner indicated. 



The following analysis of the bone of a healthy horse is to 

 be found in Bowman's Medical Chemistry. In every 100 parts 

 there is 



Phosphate of Lime 54-37 



Carbonate of Lime 12 . 00 



Phosphate of Magnesia 1 . 83 



Soluble Salts o. 70 



Cartilage 2 7 • 99 



Fat 3. 11 



100.00 



In certain morbid conditions of bone remarkable changes 

 take place in their chemical composition, in which the earthy 

 matters are so deficient th^t they no longer possess the rigidity 

 and strength necessary for sustaining the weight of the body. 

 A deficiency of the cartilaginous material would render the 

 bone brittle, and liable to fracture upon the slightest occasion. 

 The former condition is called mollities ossiwji, the latter fragi- 

 litas ossium. I have met with examples of both conditions in 

 all three bones of the feet that I have named. In healthy bone 

 phosphate of lime predominates ; in exostoses, carbonate of 

 lime is the predominating ingredient. 



GENERAL CHARACTERISTICS OF BONES. 



Bone, when recent, is covered by a very vascular membrane 

 called the periosteum. The periosteum is a bed for the ramifi- 

 cation of blood-vessels, nerves, absorbents, and is prolonged 

 into the Haversian canals, and connects itself with a similar 

 membrane within the bone named the endosteum. " Bones 



